Climate change will affect human settlements. Settlements that depend heavily on commercial
fishing, subsistence agriculture and other natural resources are particularly vulnerable. Also at
risk are low-lying areas and deltas, large coastal cities, squatter camps located in flood plains and
on steep hillsides, settlements in forested areas where seasonal wildfires may increase, and
settlements stressed by population growth, poverty and environmental degradation. In all cases, the
poorest people will be the most affected. Though climate change will often have less impact on this
sector than will economic development, technological change, and other social and environmental
forces, it is likely to exacerbate the total stress on settlements.

Infrastructure will become more vulnerable to flooding and landslides. More intense and
frequent precipitation events are expected to intensify urban flooding. The flood risks may also
increase for settlements along rivers and within flood plains. The risk of more landslides is
greatest for hillside areas.

Tropical cyclones are expected to become more destructive in some areas. Also known as
hurricanes and typhoons, these massive storm systems combine the effects of heavy rainfall, high
winds, and storm surge and sea-level rise. The risk is that warmer oceans will increase the frequency
and intensity of such storms.

Warming, dryness and flooding could undermine water supplies. Settlements in regions that are
already water-deficient – including much of North Africa, the Middle East, Southwest Asia,
portions of western North America and some Pacific islands – can be expected to face
still-higher demands for water as the climate warms. There are no obvious low-cost ways in which to
obtain increased freshwater supplies in many of these regions. In some regions, repeated flooding
could create problems with water quality.

The danger of fire could increase. However, there are many uncertainties about how hotter and
drier weather will combine with other factors to affect the risk of fire.

Agriculture and fisheries are sensitive to climate change. In some cases agricultural yields
may be reduced by up to several tens of percent as a result of hotter weather, greater evaporation,
and lower precipitation, particularly in mid-continental growing regions. However, other regions may
benefit and could experience higher yields. Fisheries will be affected because changes in ocean
conditions caused by warming can substantially impact the locations and types of target species.

Heat waves would become a greater threat to human health and productivity. Heat waves have
their most severe effects on the old, the chronically ill and the very young. The likely effects on
the overall death rate are less clear. Stronger urban heat-island effects would further exacerbate
the oppressive effects of heat waves by increasing the temperatures experienced in the summer by up
to several degrees Centigrade. Meanwhile, as the weather becomes very warm, the economic productivity
of unprotected and outdoor populations declines.

Sea-level rise will affect coastal infrastructure and resource-based industries. Many
coastlines are highly developed and contain human settlements, industry, ports, and other
infrastructure. Many of the most vulnerable regions include some small island nations, low-lying
deltas, developing countries and densely populated coasts that currently lack extensive sea and
coastal defense systems. Several industries such as tourism and recreation – the principle
earners for many island economies – are particularly dependent on coastal resources.

Energy demand is sensitive to climate change. Heating requirements at mid- and high latitudes
and altitudes would decline but cooling requirements would increase. The net overall impact of these
changes on energy use would depend on local circumstances. For example, if temperature increases take
place primarily at night and during the winter months, the demand for heating would be less, as would
the demand for cooling and for irrigation. Meanwhile, energy supply systems will be vulnerable to
changes resulting from global warming. For example, increased water deficits, less winter snowfall to
fill summer streams, and more demand for freshwater supplies would affect hydropower production.

Infrastructure in permafrost regions is vulnerable to warming. Permafrost melting is a threat
to infrastructure in these regions because it would increase landslides and reduce the stability of
foundations for structures. Other impacts would include greater damage from freeze-thaw cycles. In
addition, melting permafrost is thought to be a source of methane and carbon dioxide emissions.

Local capacity is critical to successful adaptation. The capacity of local communities to
adapt tends to be strongly correlated with wealth, human capital and institutional strength. The most
effective sustainable solutions are those that are strongly supported – and often developed
– locally. The role of higher-level bodies is then to provide technical assistance and
institutional support. A clear message for policy-makers is to always anticipate the likely future
impacts of climate change when they take decisions regarding human settlements and make investments
in infrastructure.